Bollettino valanghe

East Slopes Central

Northwest Avalanche Center
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Pericolo valanghe

Thu
Alta quota
3 · Marcato
Limite del bosco
2 · Moderato
Sotto il limite
2 · Moderato
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Non aggiornato — questo bollettino è scaduto 2 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

While we're unsure how much snow and wind this storm will bring, it will likely make triggering avalanches in steep, wind-affected terrain much easier. Consider steering around steep slopes below ridgelines with deep drifts. If you observe cracks shooting through the new snow, even in sheltered locations, default to lower-angle terrain. 

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–2

    Winds aren't terribly strong on Wednesday, but if you observe blowing snow along ridgelines or across slopes, consider avoiding steep lee slopes. Exposed terrain at upper elevations will be the most likely place to trigger a wind slab. You can identify wind-affected snow by surface texture or drifts around rocks and trees. Quick hand pits in wind-affected terrain or small steep test slopes are useful for observing how the snow reacts. Cracking or mini avalanches are signs that you could likely trigger a wind slab. 

    In more sheltered terrain, storm slabs are also possible. While we expect these to be small, there is a lot of variability and uncertainty throughout the zone. Default to more conservative slopes to give yourself some extra safety margins to account for this complex snowpack.  There is also an unlikely potential for smaller avalanches to step down to more deeply buried weak layers and be larger than you expect. Consider the consequences of triggering a large or widely propagating avalanche in the terrain you're traveling in. 

    (2/7/2025)

    An example of cracking in wind-drifted snow, signaling unstable wind slabs.  (Teanaway, 02/07).

    Photo: Payton Schiff

  • Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Unlikely
    Dimensione
    1.5–2

    While we think it's unlikely you'll find this problem in the East Central, a very large avalanche in the Snoqualmie Pass zone has us thinking the problem could still be lingering in areas closer to the Cascade Crest. In this low-likelihood, high-consequence situation, you'd be unlucky to find the right spot to trigger one of these avalanches. But the subsequent avalanche could take you for a nasty ride and/or fully bury you. 

    With persistent slab problems, signs of instability might not be apparent before triggering an avalanche. You can dig down and identify the weak, sugary snow layers 1-2ft below the recent snow and avoid slopes where you find this layering, likely on northerly aspects. If you choose to travel on steep slopes where this structure exists, consider the consequences and target more planar slopes without terrain traps.

    (2/14/2025)

    You can clearly see the grey-ish line of weak facets in the wall behind the failed snowpack test. These weak grains aren't hiding, they're easy to spot. 

    Photo: Dallas Glass

Avalanche Discussion

Another modest storm is moving into the region on Tuesday night. Models aren't in great agreement for precipitation totals, but it does look like some easterly winds and upslope components to the storm could bring 4-7 inches of snow to the zone. There is a decent chance this storm could over or underproduce by some amount, so check back on snow totals in the morning, as that could have implications for the avalanche forecast.  But let's all hope it brings more snow than expected. 

The recent storm favored the western edge of the zone, with minimal snowfall further east. At lower elevations, the warming created melt-freeze crusts on the surface and made for more unpleasant travel conditions at lower elevations. There have been minimal reports of avalanches or signs of instability, and those that occurred were small and isolated to wind-loaded terrain.  We also don't have any observations of the persistent slab problem becoming more reactive, and there have still been no confirmed persistent slab avalanches in the zone. Although the January Drought Layer (JDL) is still weak and widespread, the lack of avalanche activity is notable. We are gaining confidence that this weak layer might just not be as reactive in East Central as it is in other zones. However, with these incremental loading events, we're not quite ready to put it in the rearview mirror. 

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